Avalanche Forecast

Moderate - Intensity of incoming weather systems is uncertain

MONDAY NIGHT: Flurries, accumulation up to 20 cm, light southwest wind with moderate to strong gusts, freezing level dropping below 1000 mTUESDAY: Snow, accumulation 15-20 cm around the Duffy and 35-45 cm around the Coquihalla, light southwest wind gusting to strong, freezing level rising to 1300 mWEDNESDAY: Flurries, accumulation up to 20 cm, moderate gusting strong to extreme southwest wind, freezing level below 1000 mTHURSDAY: Snow, accumulation 30-55 cm, light to moderate ridge wind gusting to extreme, freezing level 1600 m

A MIN report Sunday from the Cayoosh area describes shooting cracks and signs of instability prior to the storm.The new storm snow has already produced small (size 1) storm slabs avalanches in the neighboring Sea to Sky region. Similar avalanche activity can be expected in the South Coast Inland as the storm progresses.Over a week ago (Saturday, Dec 1), two very large (size 3) avalanches were observed in the Joffre Lakes area. These avalanches released from the high alpine northeast and northwest faces of Mt. Joffre and Mt. Matier, respectively. The evidence of the Mt. Matier slide features several 'step downs' as the slide progressively triggered deeper layers of the snowpack, all the way down to previous summer snow cover. Both slides likely released during the previous storm. And a similar, large avalanche was also reported on Face mountain in the Hurley Pass area.

Recent snow deposited about 10 cm new snow in the region. This has buried a weak, variable layer covering 20 cm of low density faceted snow and the new snow is initially not expected to bond well with the older snow.Prior to this storm, alpine snowpack depths varied around 120-180 cm, with an early November crust at bottom of the snowpack (down 100-120cm). This crust appears to be breaking down at higher elevations and has been unreactive to snowpack tests. Snowpack depths disappear quickly with decreasing elevations.